Objective To investigate the effects of bone marrow mesenchymal stem cell-derived exosomes(BMSCs-Exo)on the regulation of epithelia-mesenchymal transition(EMT)in human peritoneal mesothelial cells(HPMCs)treated with glucose-based peritoneal dialysis fluid(PDF).Methods BMSCs-Exo were verified by transmission electron microscopy(TEM),nanoparticle tracking analyzer(NTA)and Western blot.Cultured HPMCs(HMrSV5)were divided into 5 groups;control group,high glucose-based PDF(1.5％,2.5％,and 4.25％)group,siNLRP3 group,siNC group and BMSCs-Exo treated group.Expression of E-cadherin,vimentin,α-smooth muscle actin(α-SMA)and NLRP3 inflammasome-related proteins were detected by Western blot.Real time RT-PCR was used to detected the expression of α-SMA,E-cadherin and TGF-β1 mRNAs in HMrSV5 cells.The concentration of TGF-β1,IL-1 β and IL-18 in the culture supernatant was determined by ELISA.Results The exosomes isolated were spherical and double-membrane vesicles with 40-150 nm in diameter,which expressed CD9,CD81,TSG101 and Alix protein.Our results showed that the level of α-SMA and vimentin were significantly up-regulated and E-cadherin(epithelial marker)was significantly decreased in HMrSV5 cells treated with high glucose PDF com-pared with the normal HMrSV5 cells.The expression of NLRP3,pro-caspase-1 and pro-IL-1β were also significantly up-regulated in HMrSV5 cells treated with high glucose PDF compared with the normal HMrSV5 cells.The level of TGF-β1,IL-1 β and IL-18 in high glucose PDF treated HMrSV5 cells culture supernatant was up-regulated in a dose dependent manner.The protein level of α-SMA was decreased and E-cadherin level was increased by an NLRP3 siRNA to inhibit the activation of NLRP3.Compared with 4.25％PDF treated cells,E-cadherin expression was up-regulated,while the expression of α-SMA and vimentin were down-regulated in BMSCs-Exo treatment cells(P＜0.05).Furthermore,the protein expression of NLRP3,pro-caspase-1 and pro-IL-1β in 4.25％PDF-treated HMrSV5 cells were significantly reduced by BMSCs-Exo.BMSCs-Exo also reduced the level of TGF-β1,IL-1 β and IL-8 in the 4.25％PDF-treated HMrSV5 cells culture supernatants(P＜0.05).Conclusions High glucose PDF-induced EMT in HPMCs might be mediated by NLRP3 inflammatory signaling pathway,which can be inhibited by BMSCs-Exo.